A study is proposed to determine if chronic administration of the pituitary glycoprotein follicle stimulating hormone (follitropin) results in an autoimmune response to ovarian cell membranes which contain the receptor for follitropin. The experimental animal model will be the female rat. The hypothesis suggests that antibody inactivation of the receptor and/or membrane associated entities results in gonadal failure. Inactivation may occur by 1) the receptor becoming antigenic by virtue of its association with its hormone which was involved in a primary antibody response (heterogenization); a secondary response antibody is produced which recognized the first antibody which was formed to the hormone (anti-idiotype formation). In the latter case, antibody directed against the paratope of the antihormone antibodies would interact directly with the hormone binding region of the receptor. Isotopic labelling of gonadotropin receptor in granulosa cells will be performed in order to produce an immunodiagnostic reagent to be used for the detection of receptor antibodies in serum. Initially granulosa cell membrane receptor binding parameters which characterize the initial event of the hormone-receptor interaction will be studied in control tissues. Then, the ability of putative immune sera to precipitate FSH receptors versus other membrane antigens and the effect of immune sera on gonadotropin action as well as the cytotoxicity of immune sera will be studied. The affect of administration of follitropin on serum and pituitary lutropin and follitropin levels during treatment will be determined, and ovarian and pituitary morphology will also be examined. In order to directly test the hypothesis, the effect of active immunization with purified antibody to hormone will be studied. Antisera with a positive titer for anti-idiotype will be tested for the presence of anti-receptor antibodies. Spleens of rats that exhibit positive titers for anti-idiotypes will be removed and the cells will be fused with myeloma cells. Resultant hybridomas which survive the fusion and are positive for anti-idiotypes will be expanded and used for further studies on the effects of anti-receptor antibodies an reproductive function. The current clinical use of gonadotropins for the treatment of infertility emphasizes the clinical significance of these studies. The long term goal of the grant is to determine whether or not gonadotropin receptors may be implicated in infertility of an autoallergic etiology. Understanding the processes of autoallergy or how they occur may provide new insights into the treatment of infertility as well as autoimmune diseases.